Monitoring the functions of a human or animal body is necessary in many different situations. In the past, blood samples have been taken from the patient or animal and constituents have been measured by spectrophotometry. It is also known to measure the constituents in the blood of the patient or of the animal by bringing a spectrophotometer into contact with the patient or the animal, for example by using modified contact lens systems. The eye, which is the only part of the body that is designed to transmit light, thus acts as the curvette for the spectrophotometer.
WO90/12534 describes apparatus for monitoring body functions by directing light into the eye and analysing the light returning therefrom. It also describes a pupillometer for measuring the size of the pupil. WO02/071932 describes an improvement of this apparatus in which an alignment means determines the position of the centre of the pupil using a pupillometer to assist in aligning the optical system directing light into the eye. This disclosure of both these specifications is hereby incorporated in the current specification.
The present invention aims to provide a further improvement of the apparatus described in WO90/12534 and WO02/071932.